1. Field of the Invention
The present invention relates to a method for making a production schedule for an instant process in a case where the instant process produces a plurality of types of products and supplies the products to a plurality of following processes by trucks, taking a truck delivery schedule also into account.
2. Description of the Prior Art
Japanese Patent Publication NO. SHO 63-265791 discloses a method in which a plurality of types of products (for example, engines) produced at an instant process (for example, an engine assembly line) are delivered by trucks to following processes (for example, car assembly lines) by a production schedule that determines a production number of products and a production order of different types of products, and that controls inventory or stocking by merely advancing the numbers of products needed at the following processes by periods of time necessary to deliver the products from the instant process to the following processes. When a working condition of the instant process is different from a working condition of the following process, the time to be advanced is measured on the basis of an actual working time.
However, in this prior production scheduling method, only the transportation times are taken into consideration; the numbers and times of truck deliveries are not considered. Since the flow of products will change corresponding to a change in the numbers and times of the truck deliveries, production at the instant process and the following processes may suffer a lack of supply of products from the instant process to the following process or an excess stock at the instant process or at the following process, if the truck delivery schedules are not taken into account.